如何解决Android和北欧nRF51上特有的写入故障？

Question

我正在尝试让一个安卓Nexus5X应用程序在NRF51芯片上工作，但遇到了一些问题，特别是在写入特征方面。真的希望能得到一些帮助。

我正在尝试通过应用程序在nrf上设置实时时钟(RTC)。关于关贸总协定服务特性的详细信息如下：

属性: Read - Mandatory，Write - Mandatory，WriteWithoutResponse - Excluded，SignedWrite - Excluded，Notify - Excluded，Indicate - Excluded，Write Auxilliaries Excluded，Broadcast -Excluded。

安全性: ENC_NO_MITM

描述符:无

连接到nrf后，我的'onServiceDiscovered()‘实现如下所示。我可以做一个readCharacteristic，这导致了'conCharacteristicRead()‘的调用，但是writeCharacteristic()失败了。将非常感谢您的指导。非常感谢！

public void onServicesDiscovered(BluetoothGatt gatt, int status) {

   // Get the characteristic 
   BluetoothGattCharacteristic loggingRTCCharacteristic = gatt.getService(loggingServiceUUID).getCharacteristic(loggingRTCControlPointCharacteristicUUID);
    // Read characteristic (which succeeded, as onReadCharacteristic is invoked)
    boolean successFlag = gatt.readCharacteristic(loggingRTCCharacteristic);

    // Check for success. 

    // Set a plausible timestamp.
    int year_lsb = 221; int year_msb = 7;
    int month = 3;
    int dayOfMonth = 4;
    int dayOfWeek = 7;
    int hour = 9;
    int min = 3;
    int sec = 15;

    byte[] timeStamp = {(byte)year_lsb, (byte)year_msb, (byte)month, (byte)dayOfMonth, (byte)dayOfWeek, (byte)hour, (byte)min, (byte)sec};

   logingRTCCharacteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);

    // This returns a failure. The onCharacteristicWrite() function is not invoked either.
    successFlag = gatt.writeCharacteristic(loggingRTCCharacteristic); }

Answer 1

我猜你错过了下面这行。

logingRTCCharacteristic.setvalue(timestamp)

Answer 2

确保特征数据不会超出23字节的MTU限制。因为nRF51设备的北欧堆栈(SoftDevice)仅支持23字节的最大MTU值。您的数据大小超出了23个字节。